A remark on integrability of stochastic systems solvable by matrix productansate

Within the Matrix Product Formalism we hat-e already introduced a multi-spe cies exclusion process (Phys. Rev. E, 59 (1999) 25, cond-mat/9809193), in w hich different particles hop with different rates and fast particles stocha stically overtake slow ones. In this letter we show that on an open chain, the master equation of this process can be exactly solved via the coordinat e Bethe ansatz. It is shown that the N-body S-matrix of this process is fac torized into a product of two-body S-matrices, which in turn satisfy the qu antum Yang-Baxter equation (QYBE). This solution is, to our knowledge, a ne w solution of QYBE.